Dropping the system means the city will save $39,000 in annual costs. Tedesco said the company had been pressuring the department to upgrade the system, which would have moved monitoring to California instead of in police headquarters.

"We're getting a better response from the public," Fitzgerald said about calls residents made to report gunfire.

The chief and union president said the patrol officers supported dumping ShotSpotter.

Tedesco said the system never achieved what it was suppose to do when the city installed it for $250,000 in 2009 using drug forfeiture money to cover the cost.

"It wasn't reliable," Tedesco said.

It also was expensive, the chief said. Moving one of the listening devices, he said, cost $6,500.

The system was suppose to become attuned to the way sounds were heard in Troy's streets and differentiate among the brakes of a truck climbing the Hoosic Street hill, from a firecracker, actual shots and any other noise.

Tedesco said this was never completely achieved.

Mayor Lou Rosamilia said he backed the decision to end participation in ShotSpotter.

"It's not working in the way it's suppose to," Rosamilia said.

A ShotSpotter spokeswoman could not be immediately reached Tuesday night for comment.

Troy installed a network of 22 acoustic listening devices to cover the neighborhoods with the highest crime incidents.

The city rolled out the surveillance devices with great fanfare in late 2008. It was supposed to lead officers to the sites where shots were fired when not reported by the public.

Rosamilia, Tedesco and Fitzgerald each said that unlike in some cities, Troy residents call in reports of gunshots.

At first, police touted the system as an early success. Each patrol car had access to the computerized monitoring system installed to allow officers to get the information firsthand.

It was expected to take a full year to fine-tune the acoustic devices so it would pick out the gunshots from other sounds. Tedesco said that never occurred.

The listening devices were placed to cover an area that ran from Lansingburgh south through downtown and into South Troy. The system also picked up sounds from the Rensselaer Polytechnic Institute campus.